The present invention relates to an improved method of synthesizing polyamines containing at least one olefinic polymer chain or oil soluble polyether. It concerns the improved fuel additives thereby produced, and the resultant improved fuel composition which comprises an admixture of said fuel additive and a gasoline.
It is known that oil soluble polyamines containing at least one olefinic polymer chain or oil soluble polyether can be employed to improve the detergent properties of fuel and lubricant compositions. The use of such compositions, their utility in providing a fuel with significantly reduced octane requirement increase (ORI) characteristics; removal and/or beneficial modification of deposits in the combustion chamber, intake valves and the like; as well as potential improvement in fuel efficiency are taught by a number of prior patents including U.S. Pat. Nos. 3,275,554; 4,438,757; 3,565,804; 3,574,576; 3,898,056; 3,960,515; 4,022,589; and, 4,039,300, the disclosures and claims of all of which are specifically incorporated herein by reference. Such polyamines have been used both alone and in combination with other additives, particularly polymeric additives.
The polyamines described in this invention contains at least one olefinic polymer derived from alkanes or alkenes with straight or branched chains, which may or may not have aromatic or cycloaliphatic substituents, for instance, groups derived from polymers or copolymers of olefins which may or may not have a double bond. Examples of non-substituted alkenyl and alkyl groups are polyethylene groups, polypropylene groups, polybutylene groups, polyisobutylene groups, polyethylene-polypropylene groups, polyethylene-poly-alpha-methyl styrene groups and the corresponding groups without double bonds. Particularly preferred are polypropylene and especially polyisobutylene groups, or oil soluble polyethers such as copolymers of ethylene oxide and propylene oxide.
The polyamines used to form the polyamine compounds of this invention include primary, secondary, and tertiary low molecular weight aliphatic polyamines such as ethylene diamine, diethylenetriamine, triethylenetetramine, dimethylaminopropylamine, propylene diamine, butylene diamine, trimethyl trimethylene diamine, tetramethylene diamine, diaminopentane or pentamethylene diamine, hexamethylene diamine, heptamethylene diamine, diaminooctane, decamethylene diamine, and higher homologues up to about 18 carbon atoms. In the preparation of these compounds, the same amines can be used or substituted amines can be used such as N-methyl ethylene diamine, N-propyl ethylene diamine, N,N-dimethyl 1,3-propane diamine, N-2- hydroxypropyl ethylene diamine, penta-(1-methylpropylene) hexamine, tetrabutylene-pentamine, hexa-(1,1-dimethylethylene) heptane, di-(1-methylamylene)-triamine, tetra-(1,3-dimethylpropylene)pentamine, penta-(1,5-dimethylamylene) hexamine, di(1-methyl-4-ethylbutylene)triamine, penta-(1,2-dimethyl-1-isopropyl ethylene)hexamine, tetraoctylenepentamine and the like.
Compounds possessing triamine as well as tetramine and pentamine groups are applicable for use because these can be prepared from technical mixtures of polyethylene polyamines, which could offer economic advantages.
The polyamine can be a cyclic polyamine, for instance, the cyclic polyamines formed when aliphatic polyamines with nitrogen atoms separated by ethylene groups were heated in the presence of hydrogen chloride.
The polymeric components are well known in the art and numerous patents exists which relate to their manufacture, such as U.S. Pat. No. 3,275,554.
The efficacy of the additive is a function of the nitrogen content, and/or the presence of a terminal primary amine moiety. However, terminal primary amine additives prepared according to prior art contain significant and often undesirable quantities of dimer and trimer. When terminal amine is a tertiary amine, or a sterically hindered secondary amine, there is no dimerization and the efficacy of such additives is greater than those containing dimers but inferior to additives containing only primary terminal amines.
The dimers significantly reduce the nitrogen concentration and reduce or eliminate the benefits of the nitrogen increased molecular-weight, they also result in increased overall molecular weight and higher viscosity requiring a higher concentration of additive in order to achieve the same overall effect.
Until now, those additives that are manufactured to maximize monomer concentration have generally been produced by reacting a polyolefinic halide with a substantial stoichiometric excess of amine to reduce, though not totally eliminate, the formation of dimers and trimers. The use of such a stoichiometric excess of amine, however, results in a substantial negative impact to the manufacturing costs because of the significant quantity of excess amine that must be continuously purified and recycled, and the reduction in effective reactor volume.